This invention relates to apparatus for biasing a transmission shift lever relative to a plurality of shift rails within a transmission. More particularly, the invention relates to the use of a plunger pin system designed to minimize reactive or "kick out" forces on the lever during selection of a rail.
The use of spring loaded plunger pins for achieving shift lever biasing is not new. Such devices are typically employed to align a shift lever with a "preferred" rail whenever the transmission is in neutral. Such devices also enhance the "feel" of selection, or provide "rail definition" to improve the ergonomics of the shifting process, particularly appreciated in the shifting of heavy duty truck transmissions.
Very few heavy duty transmission designs, however, provide for a noticeable force relief or "breakthrough" feel whenever a new rail position is selected. In the past, those which have been designed to provide such a feel have been expensive to manufacture. Moreover, typical breakthrough designs involve only springs and plungers, which tend to increase rather than to decrease the "kick out" forces associated with selections of chosen rails.